The Red Nucleus: Past, Present, and Future

The purpose of this review is to consider the regression of the magnocellular red nucleus and the progression of the parvocellular red nucleus.The red nucleus (RN) can be divided into two histologically distinct structures: the parvocellular red nucleus (RNp) and the magnocellular red nucleus (RNm). Literature indicates that the origin of the RN can be attributed to the advent of limbs, or limb-like structures, in lower vertebrates. Research has shown that RNm and its primary efferent pathway, the rubrospinal tract, comprise most of the red nuclei related structures from early vertebrates through the mammals.Imaging of the modern human brain displays a dominance of the RNp with marked regression of the RNm, at least related to size. The relatively large development of the RNp has been accompanied by uncertainty regarding its function in the humans.